429 lines
8.2 KiB
Markdown
429 lines
8.2 KiB
Markdown
## runc
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`runc` is a CLI tool for spawning and running containers according to the OCF specification.
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## State of the project
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Currently `runc` is an implementation of the OCI specification. We are currently sprinting
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to have a v1 of the spec out within a quick timeframe of a few weeks, ~July 2015,
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so the `runc` config format will be constantly changing until
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the spec is finalized. However, we encourage you to try out the tool and give feedback.
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### OCF
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How does `runc` integrate with the Open Container Initiative Specification?
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`runc` depends on the types specified in the
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[specs](https://github.com/opencontainers/specs) repository. Whenever the
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specification is updated and ready to be versioned `runc` will update its dependency
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on the specs repository and support the update spec.
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### Building:
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At the time of writing, runc only builds on the Linux platform.
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```bash
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# create a 'github.com/opencontainers' in your GOPATH/src
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cd github.com/opencontainers
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git clone https://github.com/opencontainers/runc
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cd runc
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make
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sudo make install
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```
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In order to enable seccomp support you will need to install libseccomp on your platform.
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If you do not with to build `runc` with seccomp support you can add `BUILDTAGS=""` when running make.
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#### Build Tags
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`runc` supports optional build tags for compiling in support for various features.
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| Build Tag | Feature | Dependency |
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|-----------|------------------------------------|-------------|
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| seccomp | Syscall filtering | libseccomp |
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| selinux | selinux process and mount labeling | <none> |
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| apparmor | apparmor profile support | libapparmor |
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### Testing:
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You can run tests for runC by using command:
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```bash
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# make test
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```
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Note that test cases are run in Docker container, so you need to install
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`docker` first. And test requires mounting cgroups inside container, it's
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done by docker now, so you need a docker version newer than 1.8.0-rc2.
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You can also run specific test cases by:
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```bash
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# make test TESTFLAGS="-run=SomeTestFunction"
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```
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### Using:
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To run a container, execute `runc start` in the bundle's root directory:
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```bash
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runc start
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/ $ ps
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PID USER COMMAND
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1 daemon sh
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5 daemon sh
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/ $
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```
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### OCI Container JSON Format:
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Below are sample `config.json` and `runtime.json` configuration files. It assumes that
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the file-system is found in a directory called `rootfs` and there is a
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user with uid and gid of `0` defined within that file-system.
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`config.json`:
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```json
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{
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"version": "0.1.0",
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"platform": {
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"os": "linux",
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"arch": "amd64"
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},
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"process": {
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"terminal": true,
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"user": {
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"uid": 0,
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"gid": 0,
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"additionalGids": null
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},
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"args": [
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"sh"
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],
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"env": [
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"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
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"TERM=xterm"
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],
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"cwd": ""
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},
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"root": {
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"path": "rootfs",
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"readonly": true
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},
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"hostname": "shell",
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"mounts": [
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{
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"name": "proc",
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"path": "/proc"
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},
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{
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"name": "dev",
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"path": "/dev"
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},
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{
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"name": "devpts",
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"path": "/dev/pts"
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},
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{
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"name": "shm",
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"path": "/dev/shm"
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},
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{
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"name": "mqueue",
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"path": "/dev/mqueue"
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},
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{
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"name": "sysfs",
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"path": "/sys"
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},
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{
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"name": "cgroup",
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"path": "/sys/fs/cgroup"
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}
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],
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"linux": {
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"capabilities": [
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"CAP_AUDIT_WRITE",
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"CAP_KILL",
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"CAP_NET_BIND_SERVICE"
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]
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}
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}
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```
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`runtime.json`:
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```json
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{
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"mounts": {
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"proc": {
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"type": "proc",
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"source": "proc",
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"options": null
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},
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"dev": {
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"type": "tmpfs",
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"source": "tmpfs",
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"options": [
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"nosuid",
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"strictatime",
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"mode=755",
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"size=65536k"
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]
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},
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"devpts": {
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"type": "devpts",
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"source": "devpts",
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"options": [
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"nosuid",
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"noexec",
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"newinstance",
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"ptmxmode=0666",
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"mode=0620",
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"gid=5"
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]
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},
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"shm": {
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"type": "tmpfs",
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"source": "shm",
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"options": [
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"nosuid",
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"noexec",
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"nodev",
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"mode=1777",
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"size=65536k"
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]
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},
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"mqueue": {
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"type": "mqueue",
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"source": "mqueue",
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"options": [
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"nosuid",
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"noexec",
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"nodev"
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]
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},
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"sysfs": {
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"type": "sysfs",
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"source": "sysfs",
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"options": [
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"nosuid",
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"noexec",
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"nodev"
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]
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},
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"cgroup": {
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"type": "cgroup",
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"source": "cgroup",
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"options": [
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"nosuid",
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"noexec",
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"nodev",
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"relatime",
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"ro"
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]
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}
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},
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"hooks": {
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"prestart": null,
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"poststop": null
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},
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"linux": {
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"uidMappings": null,
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"gidMappings": null,
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"rlimits": [
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{
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"type": "RLIMIT_NOFILE",
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"hard": 1024,
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"soft": 1024
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}
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],
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"sysctl": null,
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"resources": {
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"disableOOMKiller": false,
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"memory": {
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"limit": 0,
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"reservation": 0,
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"swap": 0,
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"kernel": 0,
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"swappiness": -1
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},
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"cpu": {
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"shares": 0,
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"quota": 0,
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"period": 0,
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"realtimeRuntime": 0,
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"realtimePeriod": 0,
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"cpus": "",
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"mems": ""
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},
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"pids": {
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"limit": 0
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},
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"blockIO": {
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"blkioWeight": 0,
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"blkioWeightDevice": "",
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"blkioThrottleReadBpsDevice": "",
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"blkioThrottleWriteBpsDevice": "",
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"blkioThrottleReadIopsDevice": "",
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"blkioThrottleWriteIopsDevice": ""
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},
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"hugepageLimits": null,
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"network": {
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"classId": "",
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"priorities": null
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}
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},
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"cgroupsPath": "",
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"namespaces": [
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{
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"type": "pid",
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"path": ""
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},
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{
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"type": "network",
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"path": ""
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},
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{
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"type": "ipc",
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"path": ""
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},
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{
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"type": "uts",
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"path": ""
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},
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{
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"type": "mount",
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"path": ""
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}
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],
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"devices": [
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{
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"path": "/dev/null",
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"type": 99,
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"major": 1,
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"minor": 3,
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"permissions": "rwm",
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"fileMode": 438,
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"uid": 0,
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"gid": 0
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},
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{
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"path": "/dev/random",
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"type": 99,
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"major": 1,
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"minor": 8,
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"permissions": "rwm",
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"fileMode": 438,
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"uid": 0,
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"gid": 0
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},
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{
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"path": "/dev/full",
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"type": 99,
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"major": 1,
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"minor": 7,
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"permissions": "rwm",
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"fileMode": 438,
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"uid": 0,
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"gid": 0
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},
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{
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"path": "/dev/tty",
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"type": 99,
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"major": 5,
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"minor": 0,
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"permissions": "rwm",
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"fileMode": 438,
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"uid": 0,
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"gid": 0
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},
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{
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"path": "/dev/zero",
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"type": 99,
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"major": 1,
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"minor": 5,
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"permissions": "rwm",
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"fileMode": 438,
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"uid": 0,
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"gid": 0
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},
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{
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"path": "/dev/urandom",
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"type": 99,
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"major": 1,
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"minor": 9,
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"permissions": "rwm",
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"fileMode": 438,
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"uid": 0,
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"gid": 0
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}
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],
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"apparmorProfile": "",
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"selinuxProcessLabel": "",
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"seccomp": {
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"defaultAction": "SCMP_ACT_ALLOW",
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"syscalls": []
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},
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"rootfsPropagation": ""
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}
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}
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```
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### Examples:
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#### Using a Docker image (requires version 1.3 or later)
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To test using Docker's `busybox` image follow these steps:
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* Install `docker` and download the `busybox` image: `docker pull busybox`
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* Create a container from that image and export its contents to a tar file:
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`docker export $(docker create busybox) > busybox.tar`
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* Untar the contents to create your filesystem directory:
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```
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mkdir rootfs
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tar -C rootfs -xf busybox.tar
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```
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* Create `config.json` and `runtime.json` using the example from above. You can also
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generate a spec using `runc spec`, which will create those files for you.
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* Execute `runc start` and you should be placed into a shell where you can run `ps`:
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```
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$ runc start
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/ # ps
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PID USER COMMAND
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1 root sh
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9 root ps
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```
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#### Using runc with systemd
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To use runc with systemd, you can create a unit file
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`/usr/lib/systemd/system/minecraft.service` as below (edit your
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own Description or WorkingDirectory or service name as you need).
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```service
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[Unit]
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Description=Minecraft Build Server
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Documentation=http://minecraft.net
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After=network.target
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[Service]
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CPUQuota=200%
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MemoryLimit=1536M
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ExecStart=/usr/local/bin/runc start
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Restart=on-failure
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WorkingDirectory=/containers/minecraftbuild
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[Install]
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WantedBy=multi-user.target
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```
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Make sure you have the bundle's root directory and JSON configs in
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your WorkingDirectory, then use systemd commands to start the service:
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```bash
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systemctl daemon-reload
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systemctl start minecraft.service
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```
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Note that if you use JSON configs by `runc spec`, you need to modify
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`config.json` and change `process.terminal` to false so runc won't
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create tty, because we can't set terminal from the stdin when using
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systemd service.
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